Probiotic agents are organisms that confer a benefit when they grow in a particular environment, often by inhibiting the growth of other biological organisms in the same environment. Examples of probiotics include bacteria and bacteriophages which can grow in the intestine, at least temporarily, to displace or destroy pathogens and provide other benefits to the host organism (Salminen et al, Antonie Van Leeuwenhoek, 70 (2-4): 347-358, 1996; Elmer et al, JAMA, 275:870-876, 1996; Rafter, Scand. J. Gastroenterol. 30:497-502, 1995; Perdigon et al, J. Dairy Sci. 78:1597-1606, 1995; Gandi, Townsend Lett. Doctors & Patients, pp. 108-110, January 1994; Lidbeck et al, Eur. J. Cancer Prev. 1:341-353, 1992). Probiotic preparations were systematically evaluated for their effect on health and longevity in the early 1900's (Metchnikoff, E., Prolongation of Life, Wilham Heinemann, London, 1910; republished by G. P. Putnam's Sons, New York, N.Y., 1970). Since the discovery and widespread use of antibiotics in about 1950 to treat pathological microbes, the use of probiotics has been limited.
The widespread use of antimicrobial drugs, especially broad spectrum antibiotics, has produced serious consequences. Individuals taking antibiotics often suffer from gastrointestinal upset when beneficial microorganisms in the gut are killed, thus changing the balance of the intestinal flora. This imbalance can result in vitamin deficiencies when vitamin-producing gut bacteria are killed and/or illness when a pathogenic organism overgrows and replaces the beneficial gut microorganisms. In addition to gut microflora, beneficial and/or pathological microorganisms can inhabit the oral cavity, the genital area and the vagina (Thomason J. L. et al., Am. J. Obstet. GynecoL 165 (4 Pt. 2):1210-1217, 1991; Marsh, P. D., Caries Res. 27 (Suppl. 1):72-76, 1993; Lehner T., Vaccine 3(1): 65-68, 1985; Hill L. V. & Embil, J. A., Can. Med. Assoc. J. 134(4):321-331, 1986). The use of antimicrobial drugs can similarly cause an imbalance in those microorganisms and the therapeutic use of probiotic bacteria, especially Lactobacillus strains, that colonize those areas has been disclosed (Winberg, J. et al., Pediatr. Nephrol. 7(5):509-514, 1993; Malin M. et al., Ann. Nutr. Metab. 40(3); 137-145, 1996; U.S. Pat. No. 5,176,911).
Increasing numbers of pathogenic microorganisms have developed antibiotic resistance, requiring the development and use of second and third generation antibiotics. Microorganisms that are resistant to multiple drugs have also developed, often with multiple drug resistance spreading between species, leading to serious infections that cannot be controlled by use of antibiotics.
Opportunistic microbial infections often occur in immunodeficient individuals. Immunodeficient individuals have impaired natural immunity allowing pathogenic microorganisms to survive and grow, either internally or externally, due to the individual's diminished immune response to the pathogen. Immunodeficiency can result from genetic conditions, diseases such as AIDS, or therapeutic treatments such as cancer therapy (chemotherapy or radiation treatment) and drug-mediated immunosuppression following organ transplant. Inhibition of pathogenic microorganisms by probiotics is useful for preventing or treating opportunistic infections, particularly in immunodeficient individuals.
Thus, there is a need for preventive and therapeutic agents that can control the growth of pathogenic microorganisms without the use of antibiotic chemicals to which the microorganisms already are or can become resistant. Probiotics can be applied either internally or externally to restore the balance of beneficial microorganisms to pathogens, without contributing to the evolution of drug-resistant pathogens.
Lactic acid producing bacteria (e.g., Bacillus, Lactobacillus and Streptococcus species) have been used as food additives and there have been some claims that they provide nutritional and therapeutic value (Gorbach S. L., Ann. Med. 22(1):37-41, 1990; Reid, G. et al., Clin. Microbiol. Rev. 3(4):335-344, 1990). Some lactic acid producing bacteria (e.g., those used to make yogurt) have been suggested to have antimutagenic and anticarcinogenic properties useful for preventing human tumors (Pool-Zobel B. L. et al., Nutr. Cancer 20(3):261-270, 1993; U.S. Pat. No. 4,347,240). Some lactic acid producing bacteria also produce bacteriocins which are inhibitory metabolites responsible for the bacteria's antimicrobial effects (Klaenhammer T. R., FEMS Microbiol Rev. 12(1-3):39-85, 1993; Barefoot S. F. & Nettles C. G., J. Dairy Sci. 76(8):2366-2379, 1993).
Selected Lactobacillus strains that produce antibiotics have been disclosed as effective for treatment of infections, sinusitis, hemorrhoids, dental inflammations, and other inflammatory conditions (U.S. Pat. No. 4,314,995). L. reuteri produces antibiotics with activity against Gram negative and Gram positive bacteria, yeast and a protozoan (U.S. Pat. No. 5,413,960 and U.S. Pat. No. 5,439,678). L. casei ssp. rhamnosus strain LC-705, DSM 7061, alone or in combination with a Propionibacterium species, in a fermentation broth has been shown to inhibit yeast and molds in food and silage (U.S. Pat. No. 5,378,458). Also, antifungal Serratia species have been added to animal forage and/or silage to preserve the animal feedstuffs, particularly S. rubidaea FB299, alone or combined with an antifungal B. subtilis (strain FB260) (U.S. Pat. No. 5,371,011).
Bacillus coagulans is a non-pathogenic gram positive spore-forming bacteria that produces L(+) lactic acid (dextrorotatory) in homofermentation conditions. It has been isolated from natural sources, such as heat-treated soil samples inoculated into nutrient medium (Bergey's Manual of Systemic Bacteriology, Vol. 2, Sneath, P. H. A. et al., eds., Williams & Wilkins, Baltimore, Md., 1986). Purified B. coagulans strains have served as a source of enzymes including endonucleases (e.g., U.S. Pat. No. 5,200,336), amylase (U.S. Pat. No. 4,980,180), lactase (U.S. Pat. No. 4,323,651) and cyclo-malto-dextrin glucano-transferase (U.S. Pat. No. 5,102,800). B. coagulans has been used to produce lactic acid (U.S. Pat. No. 5,079,164). A strain of B. coagulans (referred to as L. sporogenes Sakaguti & Nakayama (ATCC 31284)) has been combined with other lactic acid producing bacteria and B. natto to produce a fermented food product from steamed soybeans (U.S. Pat. No. 4,110,477). B. coagulans strains have also been used as animal feed additives for poultry and livestock to reduce disease and improve feed utilization and, therefore, to increase growth rate in the animals (International PCT Pat. Applications No. WO 9314187 and No. WO 9411492).